The present invention relates to a process for the preparation of chemical compounds such as alkyl glucoside, alkenyl glucoside, alkyl polyglucosides and/or alkenyl polyglucosides wherein the reaction time of said process is reduced by applying dehydrated dextrose monohydrate in a heterogeneous reaction.
The reaction of a reducing saccharide, e.g. an aldose or ketose, or a source thereof, with an alcohol results in the formation of a glycoside. Acids catalyse the reaction between a reducing saccharide and an alcohol. When the alcohol is an alkanol, the resulting glycoside is commonly referred to as an alkyl glycoside.
It is general knowledge to conduct the reaction under substantially anhydrous conditions in order to shift the chemical equilibrium to the reaction products and to avoid side-reactions such as de-acetalisation, formation of substantial quantities of undesired higher polysaccharide by-products e.g. polydextrose, and the formation of coloured bodies.
EP 0319616 describes a process for preparing glycoside products by the direct acid catalysed reaction of an aqueous saccharide solution or syrup with an alcohol reactant and without the generation of substantial quantities of undesired polysaccharide by-products by conducting said reaction in a way which prevents any aqueous saccharide solution from coming into contact with the acid catalyst during said reaction under conditions conductive to homopolymerisation of said saccharide reactant. However, this process requires a specialised set-up and the drying process has a negative effect on the quality and composition of the water-free products.
DE 42 04 699 relates to a process for producing water-free aldoses wherein aqueous syrups of starch-based products are mixed with a fatty alcohol and the total mixture is brought in a turbo-dryer at a drying temperature of between 160xc2x0 C. and 180xc2x0 C. for obtaining a melt of water-free dextrose. However, besides the melt of the water-free glucose, there is a second fraction, which is containing fatty alcohol and water that has been removed from the aqueous solution of the starch-based product. Due to the presence of water, this fatty alcohol cannot be used directly in the further processing.
DE 42 07 101 describes a process for producing alkyl and/or alkenyl glucosides wherein an aqueous solution of glucose syrup and fatty alcohol is brought into a turbo-dryer for dehydration until residual water-content of 0.05 to 0.3% is reached, followed by acetalisation in presence of acid catalyst.
DE 197 10 112 relates to a continuous process for preparing alkyl and/or alkenyl-oligoglycosides with excess of alcohol and glucose in solid form and wherein said process is performed in a reactor-cascade.
In general, dextrose monohydrate is applied for producing alkyl glucosides, and prior to the acetalisation reaction, the crystal-water of the monohydrate is removed during heating of the reaction mixture in the reactor. At least 10%, but most of the time 30% or even more of the capacity of the reactor is used for dehydration instead of the acetalisation reaction.
There is a need for an economically viable process for preparing alkyl glucosides with relative cheap dry reactants and wherein the reaction time of said process is short, and the formation of undesired by-products is reduced.
The current invention provides such a process.
The present invention relates to dehydrated dextrose monohydrate with a specific surface area of from 0.20 m2/g to 0.50 m2/g and which reduces the reaction time for preparing chemical compounds selected from the group consisting of alkyl glucoside, alkenyl glucoside, alkyl polyglucosides and alkenyl polyglucosides in a heterogeneous mixture with an alcohol. In fact, said reaction time is reduced with at least 10%, preferably 20%, more preferably 25%, most preferably with 50%.
The current invention further relates to a process for preparing chemical compounds selected from the group consisting of alkyl glucoside, alkenyl glucoside, alkyl polyglucosides and alkenyl polyglucosides wherein in said process an alcohol is reacting in a heterogeneous mixture with dehydrated dextrose monohydrate disclosed in the present invention.
The present invention relates to a process wherein the alcohol has an alkyl or alkenyl chain length selected from the group consisting of C1 to C30 and mixtures thereof.
The present invention further relates to a process, which is comprising the following steps:
a) adding dehydrated dextrose monohydrate to an alcohol containing liquid for obtaining a heterogeneous mixture,
b) Stirring the heterogeneous mixture,
c) Heating under vacuum to a temperature between 60xc2x0 C. to 180xc2x0 C., preferably between 80xc2x0 C. to 150xc2x0 C., more preferably between 95xc2x0 C. to 120xc2x0 C.,
d) Adding acid catalyst,
e) Continuing stirring at high temperature under vacuum until level of residual dehydrated dextrose monohydrate is below desired value.
f) Optionally neutralising of acid catalyst, and
g) Optionally evaporating the excess of liquid containing alcohol.
The current invention discloses a process wherein:
a) 1 weight-part of dehydrated dextrose monohydrate is added to from 2 to 10 weight-parts of C6-C25 alcohol for obtaining a heterogeneous mixture,
b) The heterogeneous mixture is heated to 80-180xc2x0 C., while stirring at 5 to 400 mbar vacuum,
c) 0.2-5% w/w (based on dry substance of dehydrated dextrose monohydrate) acid catalyst is added,
d) Continuing stirring at high temperature under vacuum until the amount of residual dehydrated dextrose monohydrate is below desired value.
The current invention further relates to a process for preparing dehydrated dextrose monohydrate by drying dextrose monohydrate wherein said dehydrated dextrose monohydrate has a specific surface area of from 0.2 m2/g to 0.50 m2/g and it reduces the reaction time for preparing in a heterogeneous reaction with an alcohol chemical compounds selected from the group consisting of alkyl glucoside, alkenyl glucoside, alkyl polyglucosides and alkenyl polyglucosides, and said process comprises the following steps:
a) Taking dextrose monohydrate,
b) Drying dextrose monohydrate at a temperature between 50 to 150xc2x0 C.,
c) Collecting dehydrated dextrose monohydrate.